JPH075421A - Liquid crystal display device and projection type display device using the same - Google Patents

Abstract

PURPOSE:To provide the liquid crystal display device and projection type display device which can obtain a high-contrast display image. CONSTITUTION:An incidence-side polarizing plate 11, 1st and 2nd phase difference plates 12 and 13 which are equal in retardation, a liquid crystal cell 14, and a projection-side polarizing plate 15 are arranged and axes 25 and 26 of polarization are crossed at right angles along rubbing directions 19 and 20. The 1st phase plate 12 crosses a main illumination light beam 24 at right angles and the 2nd phase difference plate 13 is slanted by an angle gamma from the right- angled crossing state. On a plane crossing the main illumination light beam 24 at right angles, projection components of phase delay axes 27 and 28 cross each other at right angles and are at an angle of 45 deg. to projection components of the axes 25 and 26 of polarization. Then the phase difference that the liquid crystal cell 14 applied with a specific voltage gives to the main illumination light beam 24 is canceled by the 2nd phase difference plate 13 whose angle gammais adjusted to put the light projected from the liquid crystal cell 14 closer from elliptic polarized light to linear polarized light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device which spatially modulates illumination light for displaying an image, and a projection display device using the liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, in order to display a large-screen image, there is known a method of illuminating a light valve driven according to a video signal and enlarging and projecting an optical image on the light valve onto a screen by a projection lens. ing. In recent years, a projection display device using a liquid crystal panel as a light valve is known. Many of such projection display devices employ a twisted nematic (hereinafter, TN) liquid crystal and employ an active matrix driving method in which a thin film transistor (hereinafter, TFT) is provided in each pixel as a switching element. This is mainly for obtaining a high quality projected image.
Unless otherwise specified, the TN liquid crystal panel shown below is an active matrix driven TN liquid crystal panel.

An example of the structure of a TN liquid crystal panel (FIG. 15)
Shown in. Incidence-side glass substrate 201 and emission-side glass substrate 2
02, the TN liquid crystal 203 is enclosed. On the emission side glass substrate 202, the pixel electrode 204, the TFT 205,
Gate and source signal lines (not shown) are formed. A counter electrode 206 is formed on the incident side glass substrate 201, and a black matrix 207 is formed thereon so as to cover the TFT 205 and the signal line. An alignment film 208 is formed on the pixel electrode 204 and the counter electrode 206. An arbitrary drive voltage is selectively supplied to the TFT 205 of each pixel, and the pixel electrode 204 and the counter electrode 206
An electric field according to the amount of phase modulation is applied to the liquid crystal layer 203 in between.

When no electric field is applied, the liquid crystal molecules have their molecular major axes approximately parallel to the substrate surface, and the molecular major axes are continuously twisted and oriented by 90 degrees between the upper and lower substrates. The situation is shown in (FIG. 16). A state of typical liquid crystal molecules 221 between the glass substrates 201 and 202 is schematically shown. When the alignment film is previously rubbed in the specific one of the directions 222 and 223 (rubbing treatment), the liquid crystal molecules 221 in contact with the alignment film are aligned with their long axes aligned with the rubbing direction.

In this state, when linearly polarized light having a polarization azimuth parallel or orthogonal to the long axis of the liquid crystal molecule at the incident side interface is incident, the polarization azimuth rotates (rotation) along the liquid crystal molecule and is orthogonal to the time of incidence. Then, the light is emitted as a linearly polarized light having a polarization direction.

When an electric field corresponding to the maximum driving voltage is applied,
The liquid crystal molecules 221 are untwisted, and the long axes of the molecules are oriented substantially in the normal direction of the glass substrates 201 and 202. The situation is shown in FIG. However, a slight twist remains in the liquid crystal molecules 221 near the glass substrates 201 and 202.
The molecular long axis of the liquid crystal molecule 221 in the central part of the liquid crystal layer is closest to the normal direction of the glass substrates 201 and 202, but the directions are not completely the same.

In this state, when linearly polarized light having a polarization direction parallel or orthogonal to the long axis of the liquid crystal molecules at the incident side interface is made incident, the light is emitted while maintaining the polarization direction at the time of incidence. Strictly speaking, the optical rotatory power and the birefringence are slightly left, and the light is elliptically polarized light whose major axis is oriented in the polarization direction at the time of incidence. However, the polarization component in the minor axis direction of the ellipse is much smaller than the polarization component in the major axis direction of the ellipse.

The incident side of the glass substrate 201 and the glass substrate 2
When a polarizing plate is arranged on the emission side of 02 and the respective polarization axes (polarization directions of transmitted light) are aligned with the rubbing directions 222 and 223, normally white (hereinafter, referred to as “white” when no electric field is applied) NW) mode is set. Rubbing direction 2
22 +45 degrees to the horizontal direction of the screen, rubbing direction 2
When 23 is -45 degrees with respect to the horizontal direction of the screen, the polarization axis of the incident side polarization plate and the polarization axis of the emission side polarization plate are orthogonal to each other. This is the same even when the polarizing plates on the incident side and the outgoing side are simultaneously rotated by 90 degrees.

On the other hand, there is also a configuration in which the polarization axis of the incident side polarization plate and the polarization axis of the emission side polarization plate are parallel to each other. This is a normally black (hereinafter, NB) mode in which black is displayed when no electric field is applied. Generally, the NB mode has a problem that chromaticity changes in the vicinity of black display, and thus the projection display device often uses the NW mode.

An example of the viewing angle dependence characteristic of the contrast of the NW mode TN liquid crystal panel is shown in FIG. Layer thickness is about 5
A driving voltage of about 6 V is applied to the μm liquid crystal layer. The two polarizing plates on the incident side and the outgoing side have a contrast of only the polarizing plate with respect to the light rays incident from the normal direction (light output intensity when the polarization axes of the two are parallel ÷ when the polarization axes of the two are made orthogonal to each other. The light output intensity of is 1000 is used.
The orthogonal coordinate system shown in (FIG. 16) is introduced to represent the light ray 230 of interest by using the elevation angle φ and the azimuth angle θ. The normal line of the liquid crystal layer is the Z axis, and the angle formed by this with the ray 230 is φ.
The horizontal axis of the screen is the X axis, and the angle between the projection of the light ray 230 on the XY plane and the X axis is θ. The rotation direction shows the size of the azimuth angle θ, and the radial direction shows the size of the elevation angle φ. Each concentric circle represents the elevation angle φ in increments of 2 degrees, and the outermost circle is φ =
It is 14 degrees. The contrasts of the solid line, the one-dot chain line, the broken line, the two-dot chain line, and the dotted line are 900, 700, 500, and 3, respectively.
A viewing angle of 00, 100 is shown.

From FIG. 18, the optimum viewing angle is not on the normal line of the liquid crystal layer, and the highest contrast is obtained when viewed from a slightly oblique angle of θ = 90 degrees and φ = about 3 degrees. The field of view in the horizontal display direction is relatively wider than in the vertical display direction, and θ =
The contrast in the 270 degree direction is particularly low. Although the viewing angle dependence characteristic exists for both black display and white display light transmittance, in the case of white display, the variation amount with respect to the absolute transmission amount is small. Therefore, the factor of lowering the contrast is mainly due to light leakage in black display.

Many projection type display devices using such a TN liquid crystal panel have been proposed (for example, Japanese Patent Laid-Open No. 63-
No. 73782, Japanese Patent Laid-Open No. 3-71110). An example of the configuration is shown in FIG. The liquid crystal cell 302 is illuminated by the light source 301, and the optical image on the liquid crystal cell 302 is enlarged and projected on the screen 304 by the projection lens 303. Reference numeral 305 denotes an incident side polarization plate, and 306 denotes an emission side polarization plate.

In order to obtain a high-quality projected image, it is preferable to illuminate with light that is nearly parallel to the viewing angle direction where maximum contrast is obtained. Therefore, while the liquid crystal layer 307 and the optical axis 308 of the projection lens 303 are orthogonal to each other, the screen center 309 of the liquid crystal cell 302 is located at the optical axis 30 of the projection lens 303.
Shift from 8. The direction connecting the screen center 309 and the center 311 of the entrance pupil 310 of the projection lens 303 is made to coincide with the optimum viewing angle direction, and the optical axis 312 of the illumination light flux is made to coincide with this.

When the angle formed by the optical axis 308 of the projection lens 303 and the optical axis 312 of the illumination light beam is large, the incident side polarization plate 305
By arranging the emission side polarization plate 306 perpendicularly to the optical axis 312 of the illumination light flux, a better contrast can be obtained.

There is a projection type display device using three liquid crystal panels for red, green and blue in order to obtain a higher quality projected image (for example, Japanese Patent Laid-Open No. 62-133424). An example of a two-body front system configuration in which the projector and the screen are separated is shown in FIG.

The illumination luminous flux emitted from the light source 351 is dichroic mirrors 352 and 353 and the plane mirror 35.
4 decomposes into three primary color illumination light fluxes, and the respective illumination light fluxes illuminate the liquid crystal cells 355, 356, 357. Optical images of three primary colors of red, green, and blue are formed on the liquid crystal cells 355, 356, 357, and the dichroic mirrors 358, 35 are formed.
9 and the plane mirror 360 to synthesize the projection lens 3
A full-color large-screen image is enlarged and projected on a screen (not shown) by 61. Field lens 362,
The reference numerals 363 and 364 allow the respective illumination light fluxes to effectively reach the entrance pupil of the projection lens 361. Liquid crystal cells 355, 35
The polarizing plates that should be included in Nos. 6 and 357 are included in each liquid crystal cell.

The centers of the screens of the liquid crystal cells 355, 356, 357 are displaced by a certain amount in the same direction with respect to the optical axis of the projection lens 361. As a result, the optimum viewing angle directions of the liquid crystal cells corresponding to the respective optical axes of the illumination light fluxes of the three primary colors are made coincident with each other, and a projected image with good contrast is obtained.

[0018]

The projection type display device shown in FIG. 19 can obtain a projection image with good contrast, but has a large maximum angle of view of the projection lens and biases the brightness distribution on the screen. There is a problem that occurs. The projection lens is problematic because the amount of various aberrations increases as the angle of view increases and a lens with a large aperture is required.

On the other hand, if the screen center of the liquid crystal cell is arranged on the optical axis of the projection lens, the following advantages occur. The diagonal direction of the display area of the liquid crystal cell is symmetrical with respect to the optical axis of the projection lens, and the maximum angle of view of the projection lens can be reduced. In addition, the brightness distribution of the projected image can be made close to a distribution that is close to rotational symmetry with no bias. However, in order to obtain a projected image with good contrast, it is necessary to improve the viewing angle dependence of the contrast of the liquid crystal cell.

Therefore, the fact that the optimum viewing angle direction of the liquid crystal cell does not coincide with the normal direction of the liquid crystal layer poses a serious problem in constructing the projection display device. In order to make the optimum viewing angle direction more preferable, a method of increasing the driving voltage applied to the liquid crystal layer can be considered, but this is not preferable because the power supply voltage of the driving IC increases and the amount of heat generation increases, which adversely affects the liquid crystal panel.

On the other hand, it is preferable to increase the irradiation angle of the illumination light beam and the converging angle of the projection lens in order to obtain a brighter projected image. This corresponds to making the F value of the projection lens and the illumination light flux smaller. The irradiation angle refers to an angle of a light ray that illuminates the liquid crystal panel and has the maximum inclination with the optical axis of the illumination light beam. Similarly, the converging angle refers to an angle of a light ray that has the maximum inclination with the optical axis of the projection lens among the light rays that are effectively incident on the projection lens.

From the viewing angle dependence characteristic of the contrast shown in FIG. 18, the contrast of the projected image is lowered when a light beam having a large elevation angle φ is used. Therefore, in practice, the F value of the projection lens and the illumination light flux cannot be reduced so much,
This is a big problem in obtaining a bright projected image.

On the other hand, if the projection lens is freely moved in parallel in the direction orthogonal to the optical axis by a fixed amount, the projection image can be projected on the projector body in an arbitrary oblique direction. as a result,
The relative positional relationship between the projector main body and the screen can be adjusted, and a more convenient two-body front type projection display device can be realized. Also in this case, it is a big problem that the optimum viewing angle direction of the liquid crystal panel is determined by the characteristics of the liquid crystal layer. If more light rays in directions other than the optimum viewing angle direction are used due to the parallel movement of the projection lens, the contrast of the projected image is lowered, causing a problem.

All the problems described above are common to the projection type display device shown in FIG.

[0025]

In order to solve the above-mentioned problems, a liquid crystal display device according to the present invention comprises an incident side polarization means for converting an illumination light beam into substantially linearly polarized light, and light emitted from the incident side polarization means. A liquid crystal cell that gives spatially different phase changes to each other, an emission side polarization means that mainly selectively emits only light of a specific polarization direction among the light emitted from the liquid crystal cell, the incidence side polarization means, and the liquid crystal. The liquid crystal cell is provided with a first phase difference means and a second phase difference means arranged in alignment either in the light path between the cells or in the light path between the liquid crystal cell and the emission side polarization means, and the liquid crystal cell includes a pixel electrode. The twisted nematic liquid crystal is sandwiched between the incident side transparent substrate and the emission side transparent substrate so that the twist angle is about 90 degrees, and the main polarization direction of the light emitted from the incident side polarization means is the incident side transparent substrate. Molecularly long axis substantially parallel or substantially perpendicular to the liquid crystal molecules in contact with the plate, the first phase difference means and said second phase difference means comprises approximates functionally positive uniaxial crystal,
The phase difference given by the first phase difference means to the light beam traveling orthogonally to the optical axis and the phase difference given to the light ray traveling by the second phase difference means orthogonally to the optical axis are substantially the same, and the illumination light flux is A main light ray having a representative main wavelength is referred to as a main illumination light ray, and a projection T1 of the main polarization direction of light emitted by the incident side polarization means on one plane substantially orthogonal to the main illumination light ray and the emission side polarization means. The projection T2 of the main polarization direction of the light emitted by the light source, the projection S1 of the optical axis of the first phase difference means, and the projection S2 of the optical axis of the second phase difference means.
When each of the above is defined, T1 and T2 are made substantially orthogonal, S1 and S2 are made substantially orthogonal, and
The angle formed by the optical axis of the first retardation means and the plane orthogonal to the main illumination light beam propagating in the first retardation means is defined as ψ1. The angle formed between the plane orthogonal to the main illumination light beam propagating in the two phase difference means and the optical axis of the second phase difference means is ψ2,
The angle ψ1 and the angle ψ2 are set so that the light intensity of the main illumination light beam immediately after passing through the liquid crystal cell to which a predetermined voltage is applied so as to obtain the blackest display and the emission side polarization means is minimized. At least one of them has a predetermined size which is not 0 degree and is different from each other.

According to another liquid crystal display device of the present invention, instead of the first retardation means and the second retardation means included in the above liquid crystal display device, a first-order functionally negative uniaxial crystal is approximated. The phase difference means and the second phase difference means are used.

The projection type display device of the present invention is a liquid crystal display device that modulates an illumination light flux to form an optical image, a light source that outputs the illumination light flux, and light emitted from the liquid crystal display device that is incident on the optical display. A projection lens for projecting an image on a screen is used, and the above-mentioned liquid crystal display device is used as the liquid crystal display device. Particularly, the entrance pupil of the projection lens is passed through near the center of gravity of the effective display area of the liquid crystal display device. The illumination light rays reaching the vicinity of the central portion of are defined as the main illumination light rays.

Another projection type display device of the present invention outputs three light sources including three liquid crystal display devices for respectively modulating illumination light fluxes of three primary colors to form three optical images corresponding to the three primary colors. A light source, a color separation unit that decomposes light emitted from the light source to form the illumination light fluxes of the three primary colors, and a light combining unit that combines the illumination light fluxes of the three primary colors emitted from the three liquid crystal display devices into one. A liquid crystal display device, wherein the combined illumination light flux emitted from the light combining means is incident and a projection lens for projecting the three optical images in a superposed form on a screen is provided. In particular, each of the three illuminating rays passing through the vicinity of the center of gravity of the effective display area of each of the three liquid crystal display devices and reaching the vicinity of the center of the entrance pupil of the projection lens It is as defined with the main illumination ray of the liquid crystal display device.

Still another projection display device of the present invention is a liquid crystal display device that modulates an illumination light beam to form an optical image, a light source that outputs the illumination light beam, and light emitted from the liquid crystal display device. A projection lens for projecting the optical image on a screen, the projection lens comprising means for translating in a direction substantially orthogonal to the optical axis of the projection lens, and the liquid crystal display device as the liquid crystal display device. Use, especially,
An illumination light ray that passes through the vicinity of the center of gravity of the effective display area of the liquid crystal display device and reaches the vicinity of the central portion of the entrance pupil of the projection lens is defined as a main illumination light ray, and the traveling direction changes with the movement of the projection lens. A means for changing the arrangement state of the first phase difference means or the second phase difference means provided in the liquid crystal display device is provided in accordance with the main illumination light beam to change at least one of the angle ψ1 and the angle ψ2. It was done.

[0030]

In describing the operation of the present invention, it is shown that when elliptically polarized light is incident on an appropriate linear retarder (hereinafter, retarder), it is converted into linearly polarized light. Consider the elliptically polarized light shown in (FIG. 1).

Considering a light ray traveling from the back side of the paper surface to the front side orthogonal to the paper surface, an orthogonal coordinate system is introduced with the traveling direction as the Z axis. When the electric field vector E is defined on Z = constant paper surface, the X-direction vibration component Ex and the Y-direction vibration component Ey of the electric field vector E are respectively expressed by the following equations.

[0032]

[Equation 3]

[0033]

[Equation 4]

Ax and Ay are maximum amplitudes of each, τ is a function of time and position Z, and δ is a phase difference and represents the degree of advance of Ey with respect to Ex.

The locus Q of the tip of such an electric field vector E
Is generally an ellipse. The state of elliptically polarized light can be represented by, for example, the reference azimuth on the X-axis and the amplitude ratio angle α, the ellipse major axis azimuth Θ, and the ellipticity angle β. The definition of each is shown in (Fig. 1). Specifically, the amplitude ratio angle α and the ellipticity angle β are defined by the following equations.

[0036]

[Equation 5]

[0037]

[Equation 6]

However, the amplitude ratio angle α is a value between 0 and 90 degrees. Ca is the length of the ellipse major axis LA, Cb is the ellipse minor axis L
Indicates the length of B. Positive and negative signs are used for the ellipticity angle β, which is positive for right-handed elliptically polarized light R and negative for left-handed elliptically polarized light L.

Further, there is the following relational expression among the amplitude ratio angle α, the ellipse major axis azimuth Θ, the ellipticity angle β, and the phase difference δ (Japan Society of Applied Physics, Optics Council: “Crystal Optics”, Morikita). Publishing Co.,
p121, 1975).

[0040]

[Equation 7]

[0041]

[Equation 8]

When Ax = Ay (Equation 7) is indefinite,
In this case, ellipse major axis direction Θ = 45 degrees, ellipticity angle β = δ
It becomes / 2 elliptically polarized light. The phase difference δ is ± (n-1) π
When [n is a natural number], it becomes linearly polarized light of azimuth α, and ± (n
When -1/2) π [n is a natural number], circularly polarized light is obtained.

Next, the thickness D, the refractive index in the X-axis direction is Nf,
Consider a retarder having a refractive index of Ns in the Y-axis direction. Ns>
Nf is referred to as a slow axis because the phase is relatively delayed in the direction of the refractive index Ns, and is called a fast axis because the phase is relatively advanced in the direction of the refractive index Nf. The retardation Γ is defined as the optical path length difference between the vibration component in the slow axis direction and the vibration component in the fast axis direction.
Is defined by the following formula. However, D uses the length measured along the traveling direction of the light beam.

[0044]

[Equation 9]

Using retardation Γ, the phase difference δ '(> 0) given to the ray of wavelength λ passing through it by the retarder is given by the following equation.

[0046]

[Equation 10]

When the phase difference δ of the elliptically polarized light shown in FIG. 1 is positive (the phase of the vibration component in the Y-axis direction is ahead of the phase of the vibration component in the X-axis direction), the fast axis direction of the retarder To the x-axis and the slow axis direction to the y-axis. When the phase difference δ is negative, the slow axis direction of the retarder is aligned with the x axis and the fast axis direction is aligned with the y axis. When the retardation Γ of these phase shifters is selected to satisfy the following equation and the given elliptically polarized light is made incident, the emitted light is converted into linearly polarized light. Hereinafter, the action of applying an appropriate phase shifter to elliptically polarized light to convert it into linearly polarized light having the major axis azimuth of the original ellipse as the polarization azimuth is called phase compensation.

[0048]

[Equation 11]

Since the amplitude ratio angle α differs if the way of taking the reference azimuth changes, the phase difference δ differs from (Equation 8) even if the ellipticity angle β is constant. For clockwise elliptically polarized light, set the fast axis as the reference azimuth, and for counterclockwise elliptically polarized light, set the slow axis as the reference azimuth, and rotate the retarder to change the angle between the reference azimuth and the ellipse major axis. Then, it is possible to phase-compensate arbitrary elliptically polarized light by using a retarder having an arbitrary retardation Γ. The linearly polarized light after conversion has an azimuth with an amplitude ratio angle α, but when the ellipticity angle β is small, the linearly polarized light substantially agrees with the azimuth major axis Θ.

In order to perform the phase compensation using the retarder having the smallest retardation Γ, the retarder may be arranged so that the amplitude ratio angle α becomes 45 degrees. The retarder Γ of the retarder at this time may be selected so that the phase difference δ ′ is twice the ellipticity angle β of the incident elliptically polarized light.

The operation of the present invention will be described below. When linearly polarized light is incident on the TN liquid crystal layer in the black display state, elliptically polarized light is emitted. The ellipticity angle of the emitted light is small, and the major axis direction of the ellipse is almost equal to the polarization axis direction of the incident-side polarization plate. If an appropriate phase shifter is applied to this emitted light to perform phase compensation, the polarization component transmitted through the outgoing side polarizing plate is reduced, and the light output intensity in black display is reduced. That is, the contrast can be improved. In the phase compensation, the same effect can be obtained regardless of whether the phase shifter acts on the light entering the liquid crystal layer or the light exiting from the liquid crystal layer.

Strictly speaking, the condition for performing the phase compensation is satisfied only for a light beam traveling a specific wavelength and a specific path. This is because the phase difference provided by the liquid crystal layer and the retarder has wavelength dependence and angle dependence with respect to the incident light beam. It is preferable to use a retarder having a retardation as small as possible in order to prevent the compensation deviation for light having different wavelengths and the compensation deviation for rays traveling in a different azimuth from a predetermined azimuth from becoming too large.

Therefore, it is preferable to set the amplitude ratio angle α to 45 degrees and give the same phase difference as the phase difference given by the liquid crystal layer. Generally, when linearly polarized light is incident on the TN liquid crystal layer in the black display state along the normal direction of the liquid crystal layer, the ellipticity angle β of the emitted light is about 1 to 2 degrees. For example, wavelength 5 with high visibility
For 40 nm light, retardation Γ of the retarder that compensates for this is 1.5 to 3 nm.

There is a transparent resin film stretched as a retarder which is low in cost and excellent in mass productivity. The retardation of the film currently used is about several tens of nm at the smallest, and when the retardation becomes as small as several nm, it is not practical. This is because the layer thickness becomes thin and it becomes extremely difficult to stabilize the absolute value of retardation and to improve the uniformity of retardation in the plane.

The liquid crystal display device of the present invention is provided with two retarders having a relatively large retardation, either between the incident side polarizing plate and the liquid crystal layer or between the liquid crystal layer and the emitting side polarizing plate. While making the slow axis directions of are orthogonal to each other,
At least one of the phase shifters is arranged with a slight inclination. As a result, a slight phase difference is given to the light rays passing through the two retarders to perform phase compensation, and the light output intensity during black display is reduced.

Provisionally, a first retardation plate and a second retardation plate are provided from the incident side. The same stretched transparent resin film having the same retardation is used. However, it is assumed that each retardation plate can equivalently approximate its function as a positive uniaxial crystal having an optical axis in the direction along the film surface.

Consider a light ray incident from the direction normal to the first retardation plate. Each retardation plate is arranged so as to be orthogonal to the traveling light beam and have the slow axes orthogonal to each other. in this case,
Since the second phase difference plate cancels the phase difference provided by the first phase difference plate, no phase difference occurs in the light rays transmitted through the two phase difference plates.

With the above structure, when the second retardation plate is slightly tilted with the fast axis as the rotation axis in the plane direction including the light beam which is considered as the slow axis, the phase difference given by the second retardation plate is slightly increased. Decrease. Since the phase difference given by the second phase difference plate is reduced to cancel the phase difference given by the first phase difference plate, a slight phase difference is generated in the light rays transmitted through the two phase difference plates. As a result, the effect of the retarder having a small retardation can be easily obtained equivalently. The equivalent slow axis direction is the slow axis direction of the first retardation plate.

In order to set the amplitude ratio angle α to about 45 degrees,
The slow axis directions of the first retardation plate and the second retardation plate are each made to form an angle of 45 degrees with the polarization axis of the incident side polarization plate.
The minute phase difference provided by the two phase difference plates can be adjusted by changing the inclination angle of the second phase difference plate. Specifically, the tilt angle is 1
Phase compensation can be performed by using a retardation plate having retardation of several hundreds nm at about 0 degree. As a result, the contrast can be improved.

The above-described configuration provides good phase compensation for light rays traveling in the direction normal to the first retardation plate. If this light ray is used as the main illumination light ray, it is important to reduce the residual phase difference even with respect to the light ray traveling at an angle with the main illumination light ray. If the angle formed by the light ray to be considered and the main illumination light ray is expressed as a viewing angle, the viewing angle dependence characteristic of the phase difference given by the liquid crystal layer in the black display state and the viewing angle dependence characteristic of the phase difference given by the two retardation plates are well correlated. It is preferable.

For example, (FIG. 18) is referred to as the viewing angle dependence characteristic of the phase difference provided by the liquid crystal layer in the black display state. The symmetry with respect to the main illumination ray (φ = 0 degree, θ = 0 degree) is θ = 0.
Particularly high for azimuths of degrees to 180 degrees, θ = 90 degrees to 2
Especially low for 70 degree azimuth. In the above configuration,
Since the viewing angle dependence characteristics of the phase difference provided by the two retardation plates have particularly low symmetry with respect to the slow axis azimuth of the second retardation plate to be tilted, the azimuth of θ = 90 ° to 270 ° is regarded as the same azimuth. do it. The direction in which the second retardation plate is tilted is set to a direction in which the asymmetry of the viewing angle dependent characteristics correlates well. This makes it possible to reduce the compensation deviation due to the phase difference plate inserted for a wider viewing angle range.

Next, in the projection display device of the present invention,
A ray of light that travels along the optical axis of the light source, passes through the center of the display area of the liquid crystal display device, and reaches the center of the entrance pupil of the projection lens is the main illumination ray. With the main illumination ray as the axis of rotational symmetry,
Consider a luminous flux emitted from the liquid crystal layer in a conical shape. The half apex angle of the cone corresponds to the converging angle of the projection lens and the irradiation angle of the illumination light. Consider a ray group traveling on the side surface of the cone, and describe these as the maximum tilt illumination ray group.

From FIG. 18 it is clear that the contrasts obtained for each of the maximum tilt illumination rays are not the same. In order to obtain a projected image with better contrast, it is necessary to obtain the maximum contrast for the main illuminating light beam and also obtain the same and high contrast as possible for each light beam of the maximum tilt illuminating light beam group. Therefore, it is important to improve the contrast of light rays having a particularly low contrast (hereinafter, referred to as auxiliary illumination light rays) in the maximum tilt illumination light ray group.

Normally, the phase difference given to the main illuminating light beam by the liquid crystal layer and the phase difference given to the auxiliary illuminating light beam are different, and the phase difference given to each of the two phase difference plates having the above-mentioned structure is also different.
The retardation of the two retardation plates and the tilt angle of the second retardation plate may be selected as appropriate values so as to match the respective retardations. As a result, the phase can be compensated for the main illuminating light beam as well as the phase for the auxiliary illuminating light beam. As a result, the contrast of the projected image can be improved better.

Further, let us consider a projection display device in which the projection lens can be moved in parallel in a direction orthogonal to its optical axis. When the light ray traveling along the optical axis connecting the center of the display area of the liquid crystal panel and the center of the entrance pupil of the projection lens is the main illumination light ray, the direction of the main illumination light ray changes depending on the position of the projection lens.
However, the light source is appropriately moved on the optical axis so that the main illuminating light ray travels.

Normally, the contrast of the projected image changes as the traveling direction of the main illuminating light beam changes. However, by adjusting the arrangement direction and inclination angle of the two retardation plates, the main illuminating light beam is changed regardless of the traveling direction. On the other hand, phase compensation can be performed. As a result, the contrast of the projected image can always be kept good regardless of the position of the projection lens.

[0067]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of the liquid crystal display device and the projection display device of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a constitutional view showing a first embodiment of the liquid crystal display device of the present invention. It is composed of an incident side polarization plate 11, a first retardation plate 12, a second retardation plate 13, a liquid crystal cell 14, and an emission side polarization plate 15. The liquid crystal cell 14 is a TN sandwiched between an incident side glass substrate 16 and an emission side glass substrate 17.
The rubbing direction 19 of the incident side glass substrate 16 and the rubbing direction 20 of the exit side glass substrate 17 are each +4 with respect to the horizontal direction of the screen.
The directions are 5 degrees and -45 degrees.

The Cartesian coordinate system described in FIG. 2 is introduced. The X axis and the Y axis correspond to the horizontal display direction and the vertical display direction of the liquid crystal cell 14, and the Z axis corresponds to the normal direction of the liquid crystal layer 18. The traveling direction of the light ray 21 of interest is represented using an elevation angle φ and an azimuth angle θ. The angle between the ray 21 and the Z axis is the elevation angle φ,
The angle between the projection 22 of the light beam 21 on the XY plane and the X axis is defined as the azimuth angle θ. Consider a ray 24 (φ = θ = 0 degrees) passing through the display area center 23 of the liquid crystal cell 14 along the Z-axis, and this is referred to as a main illumination ray. For convenience, the main illuminating light beam is considered as a single wavelength light having a wavelength λ.

The incident side polarization plate 11 and the emission side polarization plate 12 are
Both are orthogonal to the main illumination ray 24. Incident side polarizing plate 11
The polarization axis 25 of is the rubbing direction 1 of the incident side glass substrate 16.
9, and the polarization axis 26 of the emission side polarization plate 15 is aligned with the rubbing direction 20 of the emission side glass substrate 17. The polarization axis 25 of the incident side polarization plate 11 and the polarization axis 26 of the emission side polarization plate 15 are orthogonal to each other, and the display mode is the NW mode.

The first retardation plate 12 and the second retardation plate 13 are
A stretched transparent resin film made of polycarbonate is used, and the retarders having the same retardation Γ are used. Functionally, it can be approximated to a positive uniaxial crystal having an optical axis in the stretching direction, and the optical axis azimuth having the maximum refractive index is represented as the slow axis azimuth. The first retardation plate 12 is orthogonal to the main illuminating light beam 24 and has its slow axis azimuth 27 aligned with the X axis. The second retardation plate 13 is orthogonal to the main illumination light beam 24 and the slow axis azimuth 28 of which coincides with the Y axis,
Tilt about the X axis by an angle γ. Slow axis direction 28 is Y
-It is on the Z plane.

The function of the retardation plate made of a positive uniaxial crystal is
This will be described using the index ellipsoid 50 shown in FIG. Z '
An orthogonal coordinate system is introduced with the axis as the stretching direction and the Y ′ axis as the thickness direction. The refractive index in the X′-axis direction is Nx, the refractive index in the Y′-axis direction is Ny, and the refractive index in the Z′-axis direction is Nz. If the crystal is a positive uniaxial crystal having the Z ′ axis as the optical axis 51, Nx = Ny
<Nz. The maximum refractive index in the optical axis 51 direction is set as the slow axis direction refractive index Ns, and the minimum refractive index in the direction orthogonal to the optical axis 51 is set as the fast axis direction refractive index Nf. Ns = Nz, N
f = Nx = Ny.

A ray 5 passing through the center of gravity 53 of the index ellipsoid 50.
The phase difference given to 2 may be considered from the refractive index difference on the plane 54 orthogonal to the light ray 52. Plane 5 orthogonal to ray 52
The angle between 4 and the optical axis 51 is ψ. For the ray 52, the fast axis having the minimum refractive index is the optical axis 51 and the ray 52.
And the slow axis is the direction orthogonal to the fast axis on the plane 54. For example, if the ray 52 is on the Y′-Z ′ plane, the fast axis 55 coincides with the X ′ axis and the slow axis 56 is the projection direction of the optical axis 51 onto the plane 54. Although the refractive index in the fast axis 55 direction is Nf, the refractive index Ns' in the slow axis 56 direction is given by the following equation. Note that the angle ψ is an angle formed by the optical axis 51 and the plane 54 defined in the medium forming the retardation plate.

[0074]

[Equation 12]

Using again (FIG. 2), the function of the two retardation plates will be described. First retardation plate 12 and second retardation plate 13
In each case, the refractive index in the slow axis (optical axis) direction is Ns, the refractive index in the fast axis (orthogonal to the optical axis) direction is Nf, and the thickness is D.

Main illumination light beam 2 which has passed through the incident side polarization plate 11
4 is linearly polarized light having an azimuth of 45 degrees with respect to the X axis. The first retardation plate 12 gives a phase difference δ1 to the main illumination light beam 24. The phase difference is defined as the amount of advance of the phase of the Y-axis direction vibration component with respect to the X-axis direction vibration component. If the phase difference is negative,
The phase of the Y-axis direction vibration component is relatively delayed. The phase difference δ1 is given by the following equation.

[0077]

[Equation 13]

The second retardation plate 13 gives the main illumination light beam 24 a retardation δ2 represented by the following equation.

[0079]

[Equation 14]

However, the refractive index Ns' in the slow axis direction is shown in (Equation 12), and the angle ψ is the plane orthogonal to the main illumination light ray 24 traveling in the second retardation plate 13 and the slow axis azimuth. 28
It is the angle formed by.

The phase difference given by the first retardation plate 12 and the second retardation plate 13 is | δ1 + δ2 |, and | δ1 |> | δ2
Since |, δ1 + δ2> 0, it can be equivalently regarded as a retardation plate having the X axis as the slow axis.

Main illumination light beam 2 emitted from the second retardation plate 13
4 is a liquid crystal cell 14 driven so as to correspond to black display.
Incident on. The liquid crystal layer 18 gives the main illumination light beam 24 a minute phase difference δ0. The equivalent slow axis azimuth of the liquid crystal layer 18 is the long axis 30 of the liquid crystal molecule 29 located at the center of the liquid crystal layer 18,
It is approximately the same as the direction projected on the plane orthogonal to the traveling ray. Since the Y axis is the slow axis with respect to the main illumination light, the minute phase difference δ0 given by the liquid crystal layer 18 is negative.

Therefore, if the retardation Γ of the first retardation plate 12 and the second retardation plate 13 and the angle γ at which the second retardation plate 13 is tilted are appropriately selected, it is clear that the following equation holds. Yes, phase compensation can be realized for the main illumination ray 24.

[0084]

[Equation 15]

The second embodiment of the liquid crystal display device of the present invention will be described below with reference to FIG. The configuration shown in (Fig. 4) is
The incident side polarization plate 11 and the liquid crystal cell 14 having the structure shown in FIG.
The optical paths between are optically coupled. The incident side polarizing plate 11 and the incident side glass substrate 16 of the liquid crystal cell 14 using the closed container 35.
The space is closed and the inside of the closed container 35 is filled with, for example, a transparent silicone resin. Some transparent silicone resins are convenient because they are fluid at the time of injection and can be cured into a gel or rubber after injection. Alternatively, a transparent liquid such as ethylene glycol or silicone oil may be used. Since the glass substrate and the phase film have a refractive index of around 1.5, a transparent body having a refractive index of around 1.5 can be used as the filling material.

In particular, ethylene glycol and silicone oil are optically isotropic and convenient because they do not impart an unnecessary phase difference to a light beam passing therethrough. The same applies to the silicone resin cured in the gel form.
For example, KE1051 of Shin-Etsu Chemical Co., Ltd. can be used as the gel-like transparent silicone resin.

The configuration shown in FIG. 4 has the first retardation plate 12
And the retardation Γ of the second retardation plate 13 and the angle γ at which the second retardation plate 13 is tilted are appropriately selected, and the main illumination light beam 24
Phase compensation can be realized. However, when the optical paths before and after the first retardation plate 12 and the second retardation plate 13 are optically coupled, the following effects are obtained.

First, unnecessary reflection at the optical interface is reduced and the transmittance of the liquid crystal display device is improved. This has the advantage that a brighter optical image can be formed. Secondly, the inclination angle γ of the second retardation plate 13 can be made relatively small. When the tilt angle γ is reduced, a compact liquid crystal display device can be realized in the optical axis direction.

As described above, in the first and second embodiments of the liquid crystal display device of the present invention, the contrast of the main illuminating light beam 24 can be improved by lowering the light output intensity during black display. The phase compensation is also effective for a group of light rays forming a small angle with the main illumination light ray 24, and a liquid crystal display device having a good contrast in a desired viewing angle direction can be realized.

In the first and second embodiments of the liquid crystal display device of the present invention described above, the plane orthogonal to the main illuminating light ray 24 traveling in the second retardation plate 13 and the retardation of the second retardation plate 13 are delayed. The angle ψ formed by the phase axis 28 should preferably satisfy the following expression from (Equation 15).

[0091]

[Equation 16]

However, for the first retardation plate 12 and the second retardation plate 13, Ns is the refractive index in the slow axis (optical axis) direction,
Nf is the refractive index in the fast axis (orthogonal to the optical axis) direction, D is the thickness, and K = Nf / Ns (<1). The phase difference δ0 given by the liquid crystal layer is calculated from (Equation 8), assuming that the amplitude ratio angle α = 45 degrees. The ellipticity angle β with respect to the main illumination light beam 24 emitted from the liquid crystal cell 14 in the black display state in the state where the first retardation plate 12 and the second retardation plate 13 are not provided in advance.
And δ0 = 2β. However, from the above definition, the phase difference δ0 is negative.

The third embodiment of the liquid crystal display device of the present invention will be described below with reference to FIG. The configuration shown in (Fig. 5) is
The case where the transparent resin film which can functionally approximate a negative uniaxial crystal having an optical axis in the stretching direction is used as the first retardation plate 41 and the second retardation plate 42 is shown. Examples of such a film material include polystyrene. The other configurations except the first retardation plate 41 and the second retardation plate 42 and the definition of the Cartesian coordinate system to be introduced are the same as those shown in (FIG. 2), and the main illumination light ray 24 is a single Wavelength light.

The first retardation plate 41 and the second retardation plate 42 are
The same retardation film having the same retardation Γ, the first retardation film 41 is orthogonal to the main illumination light beam 24, and the fast axis azimuth 43 thereof is matched with the Y axis. The second retardation plate 42 is orthogonal to the main illumination light beam 24 and its fast axis azimuth 44 is X.
From the state where it is aligned with the axis, tilt by the angle γ ′ around the Y axis. The fast axis azimuth 44 is on the XZ plane. The fast axis azimuth means the azimuth having the minimum refractive index in the retardation plate, that is, the optic axis azimuth.

The function of the retardation plate made of a negative uniaxial crystal is
The index ellipsoid 50 shown in (FIG. 3) will be referred to again and supplemented. When the refractive index ellipsoid 50 represents a negative uniaxial crystal whose optical axis is the Z ′ axis, Nx = Ny> Nz for refractive indices Nx, Ny, and Nz. Therefore, regarding the first retardation plate 41 and the second retardation plate 42 of the present embodiment, the minimum refractive index in the optical axis 51 direction is set to the fast axis direction refractive index Nf,
The maximum refractive index in the direction orthogonal to the optical axis 51 is defined as the slow axis direction refractive index Ns. That is, Ns = Nx = Ny, Nf = N
z.

As in the case of the positive uniaxial crystal, the refractive index on the plane 54 is used as the phase difference given to the light beam 52. However,
The angle formed by the optical axis 51 and the plane 54 orthogonal to the light ray 52 is represented by ψ ′. For ray 52, coincident with the X'axis 5
5 is regarded as a slow axis, and the projection azimuth 56 of the optical axis 51 onto the plane 54 is regarded as a fast axis. Although the refractive index in the slow axis direction is Ns, the refractive index Nf 'in the fast axis direction is given by the following equation.

[0097]

[Equation 17]

Using again (FIG. 5), the function of the two retardation plates will be described. However, the thickness of the first retardation plate 41 and the second retardation plate 42 is D. The first retardation plate 41 gives a phase difference δ1 ′ represented by the following equation to the main illumination light ray 24 that has passed through the incident side polarization plate 11.

[0099]

[Equation 18]

The second retardation plate 42 gives the main illumination light beam 24 a phase difference δ2 'represented by the following equation.

[0101]

[Formula 19]

However, the refractive index Nf 'in the fast axis direction is (Equation 1
As shown in 7), the angle ψ ′ is an angle formed by the main illumination light ray 24 traveling in the second retardation plate 42 and the fast axis azimuth 44.

The phase difference given by the first retardation plate 41 and the second retardation plate 42 is | δ1 '+ δ2' |, and | δ1 '|>
Since it is clear that | δ2 ′ | and δ1 ′ + δ2 ′> 0, it can be equivalently regarded as a retardation plate having the X axis as the slow axis, similarly to the configuration shown in FIG.

Therefore, if the retardation of the first retardation plate 41 and the second retardation plate 42 and the angle γ'for inclining the second retardation plate 41 are appropriately selected, the following equation is apparently established. Yes, phase compensation can be realized for the main illumination ray 24.

[0105]

[Equation 20]

The angle ψ ′ formed by the plane orthogonal to the main illuminating light ray 24 traveling in the second retardation plate 42 and the fast axis 44 of the second retardation plate 42 is preferably expressed by the following equation (20). You just have to meet.

[0107]

[Equation 21]

However, K '= Ns / Nf (> 1). The retardation δ0 given by the liquid crystal layer is the same as that described in the case of (Equation 16).

An example of a more preferable constitution of the liquid crystal display device of the present invention will be described below. The first retardation plate and the second retardation plate are preferably retardation plates that are functionally approximated by a positive uniaxial crystal, and the second retardation plate is, for example, in the embodiment shown in (FIG. 4). The direction in which the phase difference plate 13 is inclined is such that the angle formed by the normal line 36 of the second phase difference plate 13 and the long axis 30 of the liquid crystal molecule 29 located in the center of the liquid crystal layer 18 in the black display state is smaller. Stipulate in particular.

The reason for this will be described with reference to FIGS. 6 and 7. (FIG. 6) shows a cross section in the YZ direction of the configuration shown in (FIG. 4), and (FIG. 7) shows a cross section in the XZ direction of the configuration shown in (FIG. 4). 12 and the second retardation plate 13 are each schematically shown. For convenience, it is assumed that the liquid crystal cell 14, the first retardation plate 12 and the second retardation plate 13 are in a medium having a refractive index close to these, and refraction of light rays at each interface can be ignored.

The main illuminating light ray 24 and the light ray 6 traveling at a constant angle with the main illuminating light ray 24 on the respective cross-sectional views.
Consider 1, 62, 63, 64. Rays 61, 62, 6
3, 64 intersect the main illumination ray 24 at the center of the liquid crystal layer 18. To simplify the description, the liquid crystal layer 1 in the black display state
The function of 8 is represented by the liquid crystal molecule 29 located in the center of the liquid crystal layer 18. This approximation is sufficiently valid to characterize the function of the liquid crystal layer required for this description.

Consider the viewing angle dependence characteristic of the phase difference provided by the liquid crystal layer 18 in the black display state. However, the viewing angle indicates an angle formed by the focused light beam and the main illumination light beam 24. The long axis 30 of the liquid crystal molecule 29 is approximately on the YZ plane and forms a predetermined angle with the Z axis. The direction is uniquely determined from the rubbing direction of the liquid crystal cell 14. The liquid crystal molecules 29 give the same amount of phase difference with high symmetry to the light rays 63 and 64 traveling on the XZ plane. On the other hand, the phase difference given to the ray 61 traveling on the YZ plane is larger than the phase difference given to the ray 62. Therefore, the viewing angle dependence characteristics of the phase difference provided by the liquid crystal layer 18 include a direction with high symmetry (XZ plane direction) and
In particular, there is a direction with low symmetry (YZ plane direction).

On the other hand, consider the viewing angle dependence characteristic of the phase difference provided by the two retardation plates. Since the first retardation plate 12 and the second retardation plate 13 give the same amount of phase difference to the light ray 63 and the light ray 64 having the same incident angle, they have high symmetry in the XZ plane direction. On the other hand, the second retardation plate 13 tilted in the YZ plane direction gives the light beams 61 and 62 having different incident angles different phase differences. Therefore, the symmetry is low in the YZ plane direction, and the direction in which the second retardation plate 13 is tilted is particularly important. In order to reflect the magnitude relation of the phase difference given by the liquid crystal layer 18 and make the phase difference given to the ray 61 larger than the phase difference given to the ray 62, the second retardation plate 13
Is tilted in a direction in which the angle formed by the long axis 30 of the liquid crystal molecule 29 and the normal line 36 becomes smaller.

Therefore, the relative relationship between the liquid crystal cell 14 and the second retardation plate 13 to be tilted as described above is such that the viewing angle dependence characteristic of the retardation given by the liquid crystal layer 14 in the black display state and the first retardation plate 12 The viewing angle dependence characteristics of the phase difference provided by the second phase plate 13 are well correlated. As a result, it is possible to reduce the deviation of the phase compensation for the light rays that travel at an angle with the main illumination light ray 24, so that good contrast is obtained in a wider viewing angle range.

The first embodiment of the projection display device of the present invention will be described below with reference to FIG. Reference numeral 101 denotes the liquid crystal display device of the present invention shown in FIG.
The first retardation plate 12, the second retardation plate 13, the liquid crystal cell 14,
The emission side polarization plate 15 and their configurations are the same. The optical path between the incident side polarization plate 11 and the liquid crystal cell 14 is a closed container 35.
It is hermetically sealed by and is filled with ethylene glycol and optically coupled. The optical image on the liquid crystal display device 101 is the light source 10
It is illuminated by 2 and is enlarged and projected on the screen 104 by the projection lens 103.

The light travels along the optical axis of the light source 102, passes through the center 109 of the display area of the liquid crystal display device 101, passes through the center 106 of the entrance pupil 105 of the projection lens 103, and reaches the center 107 of the screen 104. Main light ray 10
8 The main illuminating light beam 108 simultaneously travels along the normal line of the liquid crystal layer 18 and the optical axis of the projection lens 103.

Since the liquid crystal display device 101 can satisfactorily phase-compensate the main illuminating light beam 108 passing through the liquid crystal layer 18 in the black display state, the projection display device of the present invention can project a projected image with excellent contrast. Therefore, for example, the tilt angle of the second retardation film 13 may be adjusted so that the brightness of the projected image in the black display state becomes the darkest.

The projection lens 103 is preferably a projection lens having high telecentricity. A projection lens with high telecentricity means that the chief ray at any angle of view is parallel to the optical axis of the projection lens. This is because the condition in which the phase compensation is performed for the main illumination light beam 108 passing through the center 109 of the display area of the liquid crystal display device 101 is
This is convenient because it holds for the chief ray in the entire display area. That is, it is possible to realize a projection display device in which the contrast is improved satisfactorily over the entire projected image.

The liquid crystal display device 101 can improve the contrast of light rays incident from the direction normal to the liquid crystal layer 18. Since the projection lens 103 does not need to be off-axis with respect to the display area of the liquid crystal display device 101, it is possible to use a projection lens having a small angle of view and obtain a projected image with less uneven brightness even in the peripheral portion.

In all the embodiments of the liquid crystal display device described above, the main illuminating light beam is described as a single-wavelength light of wavelength λ, but in general, the light for illuminating the liquid crystal display device has a certain wavelength band. A compensation shift occurs for light with different wavelengths,
The effect of the present invention can be sufficiently obtained by implementing the phase compensation for the wavelength that represents the wavelength band of the illumination light. For example, in the case of a liquid crystal display device that modulates light in the entire visible light range, a configuration may be adopted in which the phase is optimally compensated for a wavelength of around 540 nm, which has high visibility. The same applies to the projection display device of the present invention.

The second embodiment of the projection type display device of the present invention will be described below with reference to FIG. This is an example of a configuration for obtaining a higher-quality full-color projection image by using three liquid crystal display devices corresponding to the three primary colors. By limiting the illumination light of the liquid crystal display device to a specific primary color light, the problem of compensation shift for light of different wavelengths can be reduced.

Illumination light emitted from the light source 124 is converted into red, blue and green by dichroic mirrors 125 and 126.
The corresponding liquid crystal display device 121 is decomposed into primary color illumination light,
Illuminate 122 and 123. The plane mirror 127 is used to bend the optical path. Liquid crystal display device 121, 12
Illumination light illuminating 2, 123 is effectively transmitted to the entrance pupil 136 of the projection lens 134 by the field lenses 128, 129, 130 which are weak converging lenses.
The optical images of the three primary colors on the liquid crystal display devices 121, 122, 123 are combined by the dichroic mirrors 131, 132 and the plane mirror 133, and a full-color projection image is enlarged and projected on a screen (not shown).

Before and after each of the liquid crystal display devices 121, 122 and 123, consider three main illuminating light beams 141, 142 and 143 having wavelengths representative of each of the three primary colors. The main illuminating rays 141, 142, 143 correspond to the corresponding liquid crystal display device 1.
A light ray that passes through the center of the display area of 21, 122, and 123 and reaches the center 137 of the entrance pupil 136 of the projection lens 134, the optical axis of the light source 124, and the corresponding field lens 12.
8, 129, 130 optical axis, projection lens 134 optical axis,
Follow along.

The liquid crystal display devices 121, 122 and 123 are
For example, the liquid crystal display device shown in (FIG. 4) realizes phase compensation in the black display state for the main illumination rays 141, 142, and 143 corresponding to each. Main illumination light beam 141,
Although the wavelengths of 142 and 143 are different, the conditions for realizing the phase compensation are different, but it is possible to realize the phase compensation suitable for each wavelength by adjusting the inclination angle of the second retardation plate. As a result, red,
An optical image with good contrast can be obtained for both green and blue, and a high-quality projected image with excellent contrast can be realized.

Since a projection lens having a small angle of view can be used as the projection lens 134, it is possible to obtain a projection image that is bright to the peripheral portion and has less uneven brightness. Further, since each of the liquid crystal display devices corresponding to the three primary colors can be composed of the same component, it is possible to realize a projection display device excellent in cost and mass productivity.

The third embodiment of the projection type display device of the present invention will be described below. In the configuration shown in FIG. 9, it is assumed that the projection lens 134 can be arbitrarily translated in a predetermined range in the direction orthogonal to its optical axis. While moving the light source 124 in accordance with the parallel movement of the projection lens 134,
The arrangement direction of at least one of the first retardation plate and the second retardation plate included in each of the liquid crystal display devices 121, 122, 123 is changed. The light source 124 is moved so that the extension of its optical axis always reaches the center 137 of the entrance pupil 136 of the projection lens 134.

The main illuminating light rays 141, 142, 143 travel along the optical axis of the light source 124, pass through the center of the corresponding display area of the liquid crystal display device 121, 122, 123, and enter the entrance pupil 136 of the projection lens 134. The light ray reaches the center 137. The traveling directions of the main illuminating light rays 141, 142, 143 change as the projection lens 134 moves in parallel.
If the arrangement direction of at least one of the retardation plate and the second retardation plate can be changed, the phase compensation in the black display state can always be realized for the main illumination light beam.

Therefore, the above configuration has an advantage that the projection image can be projected in an arbitrary oblique direction and the degree of freedom in installing the projector main body with respect to the screen can be increased. At the same time, even if the projection lens is moved in parallel, the contrast of the projected image can always be kept good.

A second embodiment of the liquid crystal display device of the present invention shown in FIG. 4 and a first embodiment of the projection display device of the present invention shown in FIG. 8 will be described below. Experiment 1 was conducted and its effect was confirmed. Experiments, especially at wavelength 540
This was done using a light source that emits green light with a strong spectrum near nm.

The incident side polarization plate 11 and the emission side polarization plate 15 are
A polarizing plate made of a stretched polyvinyl alcohol film adsorbing iodine was attached to a glass substrate as a polarizing element. The incident side polarization plate 11 with respect to the main illumination light beam 24
When only the output side polarization plate 15 is arranged, the contrast (light output intensity when the polarization axes 25 and 26 are parallel / light output intensity when the polarization axes 25 and 26 are orthogonal) is:
It was about 1000.

The first retardation plate 12 and the second retardation plate 13 are
In each case, a glass plate having a retardation plate made of a polycarbonate film attached thereto was used. This is a retardation plate that can be functionally approximated to a positive uniaxial crystal having an optical axis in the direction along the film surface, and a refractive index Ns in the slow axis (optical axis) direction is about 1.589. The refractive index Nf in the fast axis (perpendicular to the optical axis) direction was about 1.582.
The thickness D was selected so that the retardation Γ was 200 nm. However, each value is a value for a wavelength of 540 nm.

The liquid crystal cell 14 was constructed using a general TN liquid crystal material. The liquid crystal layer 18 has a gap thickness of 5 μm, and a driving voltage of about 6 V was applied to obtain a black display state. When no drive voltage was applied, the white display was performed. First retardation plate 1
The ellipticity angle β of the main illuminating light beam 24 immediately after being emitted from the liquid crystal cell 14 without the second and second retardation films 13 was about 1 degree.

In the state where the first retardation plate 12 and the second retardation plate 13 are not provided, the contrast (light output intensity in white display state /
When the light output intensity in the black display state) was measured, it was about 600 for the main illumination light beam. The viewing angle dependence characteristics of the contrast in this case were almost the same as those shown in FIG. 18, and the viewing angle dependence characteristics were biased in the specific direction (θ = 90 degrees to 270 degrees). A liquid crystal display device without a retardation plate and a projection type display device shown in FIG. 8 using a projection lens having an F value of 4 are formed.
The contrast (light output intensity in white display state / light output intensity in black display state) measured in 7 was about 200.

A first retardation plate 12 and a second retardation plate 13 were added, and the optical paths between the incident side polarizing plate 11 and the incident side glass substrate 16 of the liquid crystal cell 17 were filled with ethylene glycol for optical coupling. When the second retardation film 13 was tilted so that γ = 10 degrees, the light output intensity of the main illumination light beam 24 in the black display state became the minimum. The contrast was then improved to 900 for the main illumination ray 24.

When the viewing angle dependence of contrast was measured, the results shown in FIG. 10 were obtained. The rotation direction in FIG. 10 represents the magnitude of the azimuth angle θ, the radial direction represents the magnitude of the elevation angle φ, and each concentric circle represents the elevation angle φ in steps of 2 degrees. The outermost circle is φ = 14 degrees. Solid line, dash-dotted line,
The contrast of the broken line, the chain double-dashed line, and the dotted line is 90
The viewing angles are 0, 700, 500, 300, 100. Despite a slight deviation, the main illuminating light beam (φ = 0 degree, θ
(About 0 degree), a viewing angle dependence characteristic close to rotational symmetry was obtained, and the bias of the contrast in the specific viewing angle direction was improved.

The above-described phase-compensated liquid crystal display device and F
When the projection display device shown in FIG. 8 was constructed using a projection lens having a value of 4, the contrast measured at the center 107 of the screen 104 was improved to about 300.

A particularly preferable structure of the first embodiment of the projection type display device of the present invention shown in FIG. 8 will be described below. The same applies to the embodiments of the liquid crystal display device of the present invention shown in (FIG. 2) and (FIG. 4).

The liquid crystal display device 101 is constructed so as to satisfy the condition for favorably compensating the phase of the main illumination light beam 108. The condition is that the first retardation plate 12 and the second retardation plate 1 are used.
It does not uniquely determine the retardation Γ of 3.
Regarding the retardation Γ of the retardation film and the inclination angle γ of the second retardation film 13, there are a plurality of combinations that satisfy the above conditions.

The first condition is to perform good phase compensation for the main illuminating light beam 108, and the more optimum values for the retardation Γ and the tilt angle γ of the retardation plate are taken into consideration in consideration of the second condition described below. Is preferably selected. Less than,
The second condition to be satisfied by the liquid crystal display device 101 will be described.

As a light ray group used by the projection lens 103, consider, for example, a cone having the center 109 of the display area as an apex and the main illumination light ray 108 as an axis of rotational symmetry. If the F value of the projection lens 103 is 4, the converging angle of the projection lens 103 is about 7 degrees, and the apex angle of the cone is about 7 degrees. In order to obtain a projected image with good contrast, it is necessary to obtain a high contrast on average for the rays included in the cone. For that purpose, it is important to perform phase compensation on a light ray having the lowest contrast (hereinafter referred to as auxiliary illumination light ray) among the light rays included in the cone, and the phase compensation is performed by the second light ray which the liquid crystal display device 101 must satisfy. The condition of. Specifically, a light ray with an elevation angle φ = 7 degrees and an azimuth angle θ = 270 degrees is used as an auxiliary illumination light ray. However, the definitions of the elevation angle φ and the azimuth angle θ follow those shown in (FIG. 4).

The procedure for performing the phase compensation for the auxiliary illumination light beam is the same as that for the main illumination light beam 108. First
The ellipticity angle β ′ immediately after being emitted from the liquid crystal cell 14 by entering the auxiliary illumination light beam without the retardation plate 12 and the second retardation plate 13 is clarified. A plane orthogonal to the auxiliary illumination light ray traveling through the second retardation plate 13 and the second retardation plate 13
If the angle formed by the optical axis of is considered as ψ in (Equation 12), the first
The phase difference provided by the retardation plate 12 and the second retardation plate 13 can be known in the same manner as in (Equation 13) and (Equation 14). Then, the phase difference δ corresponding to the above ellipticity angle β '
It is sufficient to satisfy (Equation 15) for 0 '.

In other words, for the main illumination light beam 108, the retardation Γ and the tilt angle γ satisfying the above first condition.
It is only necessary to clarify the combination and to select the auxiliary illumination light beam that satisfies the second condition above. In this case, it is not necessary to strictly perform phase compensation for the auxiliary illumination light beam, and the residual phase difference may be reduced as much as possible before the phase difference plate is provided.

A second experiment conducted to confirm the effect of improving the contrast in the projection type display device having the above configuration will be described below. The second experiment is the first retardation plate 12
And the magnitude of the retardation Γ of the second retardation plate 13 and the magnitude of the inclination angle γ of the second retardation plate 13,
The same parts, the same configuration, and the same procedure as those of the experiment were performed.

In a state where the first retardation plate 12 and the second retardation plate 13 are not provided, the main illumination light beam 108 and the auxiliary illumination light beam (φ =
7 degrees, θ = 270 degrees), and the ellipticity angle immediately after exiting from the liquid crystal cell 14 was measured. Β = 1 degree,
β '= 5.5 degrees. When I measured the contrast,
It was about 600 for the main illuminating ray 108 and about 60 for the auxiliary illuminating ray.

The first retardation plate 12 and the second retardation plate 13 are
The same stretched transparent resin film made of polycarbonate as that used in the first experiment was used, and only the thickness D was changed to give a retardation Γ of 5 for light with a wavelength of 540 nm.
00 nm. This is because, from various studies, when the retardation Γ was set to 500 nm, the contrast of the auxiliary illumination light beam was most improved.

The first retardation plate 12 and the second retardation plate 13 are
The second retardation film 13 is added in the same manner as in the first experiment, and
The light output intensity of the main illuminating light beam 108 in the black display state became the minimum when tilted so as to be 7 degrees. The contrast at that time is about 900 for the main illumination light beam 108,
Improved to about 250 for auxiliary illumination light. When the ellipticity angle of the auxiliary illumination light beam immediately after exiting the liquid crystal cell 14 was measured, it was confirmed that β was reduced to 1.5 °.

For comparison, the first experiment was repeated for the auxiliary illumination light beam and the contrast was measured.
It was 50. Therefore, it was found that the configuration used in the second experiment can improve the contrast of the auxiliary illumination light beam more than the configuration used in the first experiment. The result of measuring the viewing angle dependence of the contrast is shown in FIG.
(FIG. 11) draws isocontrast curves in the same way as (FIG. 10). Compared with the result of the first experiment shown in (FIG. 10), the viewing angle dependence of contrast was better improved.

When the projection type display device shown in FIG. 8 was constructed by using the liquid crystal display device having better phase compensation and the projection lens having the F value of 4, the measurement was made at the center 107 of the screen 104. The contrast was improved to about 400.

Other desirable structural examples of the liquid crystal display device of the present invention will be described below. The first retardation plate and the second retardation plate included in the liquid crystal display device of the present invention may be held by the transparent body 151 shown in (FIG. 12). Transparent body 15
Reference numeral 1 is made of glass or transparent plastic such as acrylic, and is provided with a first retardation plate 154 and a second retardation plate 155 on opposing surfaces 152 and 153. In the case of a retardation plate made of a stretched transparent resin film, each phase film may be attached via an adhesive layer.

However, the surface 152 is orthogonal to the main illuminating light ray 160 which is incident on the surface 152, and the surface 153 is the facing surface 1.
Tilt with respect to 52. The tilting direction and the tilting angle are matched with the tilting direction and the tilting angle of the second retardation plate in each of the above embodiments. Side surfaces 156, 157, 158, 1
It is convenient for holding the transparent body 151 if any one of the 59 is orthogonal to the non-tilted surface 152. This is because the first phase difference plate and the second phase difference plate can be easily held, and when two phase difference plates are provided, the interface can be changed from four faces to two faces, so that the transmittance can be increased. There are advantages.

The first retardation plate and the second retardation plate included in the liquid crystal display device of the present invention may be held by the transparent bodies 171 and 172 shown in FIG. Transparent body 171
And 172 have a configuration in which a rectangular parallelepiped is divided by inclined surfaces 173 and 174. The first retardation plate 175 is affixed to the surface 177 of the transparent body 171, and the second retardation plate 176 is the transparent body 171.
173 and the surface 174 of the transparent body 172.

However, the surface 177 is orthogonal to the main illuminating light ray 179 incident on the surface 177, and the inclined surfaces 173 and 174.
The inclination direction and the inclination angle of the
Match the direction and the tilt angle of the retardation plate. The surfaces 177 and 178 of the combined transparent bodies 171 and 172 are parallel to the liquid crystal layer, the incident side polarization plate is on the opposite surface 180 of the first retardation plate 175, and the incidence side glass substrate of the liquid crystal cell is on the surface 178. If they are adhered via the adhesive layers, the same effect as the optical coupling in the embodiment shown in FIG. 4 can be obtained.

In the case where the main illuminating light beam is a light beam that makes an angle with the normal line of the liquid crystal layer, it is effective to transform the structure shown in FIG. 13 into the structure shown in FIG. Instead of the transparent body 172, this is a surface 181 corresponding to the liquid crystal cell side.
Is used with respect to the surface 177.
However, the surface 177 is the main illumination light ray 18 that travels in a predetermined direction.
2 and the surface 181 is orthogonal to the normal line 183 of the liquid crystal layer.

Since the first retardation plate 175 is attached to the surface 177 on the incident side, it can be held orthogonal to the main illuminating light beam 182. Since the surfaces 173 and 174 to which the second retardation plate 176 is attached are inclined with respect to the surface 177 by a predetermined amount in a predetermined direction, the second retardation plate 176 can be correctly and easily held. When the exit side surface 181 is inclined in this way, it can be bonded to the entrance side glass substrate of the liquid crystal cell via the adhesive layer, and thus there is an advantage that optical coupling can be easily performed.

In particular, the surface 177 on the incident side is provided with the main illumination light beam 18
When made orthogonal to 2, the symmetry of the light rays traveling at the same angle as the main illumination light ray 182 in the air is determined by the first retardation plate 1
75, the second retardation film 176, and the liquid crystal cell are also stored in the medium. This is convenient for correlating the visual dependence characteristic of the phase difference provided by the liquid crystal layer in the black display state with the visual dependence characteristic of the phase difference provided by the two retardation plates.

It has been found that the retardation of each of the first retardation plate and the second retardation plate is preferably 100 nm or more and 1000 nm or less with respect to light having a wavelength of 540 nm with high visibility. If a retardation plate having a retardation of less than 100 nm is used, the angle at which the retardation plate is tilted becomes too large and there is a problem. The optical path occupied by the tilted phase difference plate becomes large, and a compact liquid crystal display device in the depth direction cannot be realized. If a retardation plate having a retardation of more than 1000 nm is used, there is a problem that the sensitivity becomes too high when adjusting the tilt angle of the retardation plate. Moreover, a large phase compensation shift occurs due to a slight characteristic variation and an element placement error, and the contrast cannot be improved satisfactorily.

For example, in the configuration shown in FIG. 4, a case will be described in which the elliptically polarized light having the ellipticity angle β = 1 ° is phase-compensated.
When a retardation plate having a retardation of less than 100 nm was used, the second retardation plate had to be tilted by about 15 degrees or more. When a retardation plate having a retardation of more than 1000 nm was used, the optimum position of the second retardation plate was examined within the tilt angle of about 4 degrees or less, but the sensitivity was too high to improve the contrast satisfactorily. . In either case, it can be said that the inclination angle of the second retardation plate is a value that is not practical.

The inclination angle γ or γ ′ of the second retardation plate may not strictly satisfy (Equation 16) or (Equation 21). For example, a mechanism for changing the inclination of the second retardation plate in a predetermined direction within a predetermined range may be provided, and the inclination angle may be adjusted so that the light output in the black display state is minimized. This has the advantage that the phase compensation can be performed under more optimal conditions even if there are variations in the characteristics of each element or placement errors. For this reason, it is preferable that the first retardation plate and the second retardation plate that are particularly inclined be separated from the incident side polarization plate, the liquid crystal cell, and the emission side polarization plate, and the arrangement state be variable.

When optically coupling the space around the first retardation plate and the second retardation plate, the use of a transparent liquid or gel silicone rubber as the optical coupling material has the following advantages. In particular, a transparent liquid is preferable because the arrangement state of the retardation plate can be freely adjusted with the transparent liquid being filled.
Even if a gel-like silicone rubber is deformed, if the deformation amount is small, peeling or cracking does not occur, and almost no birefringence occurs inside. Therefore, even if the silicone gel is filled around the retardation plate, the arrangement state of the retardation plate can be finely adjusted, which is preferable.

In all of the above-mentioned embodiments, the case where the second retardation plate located on the side closer to the liquid crystal layer is tilted has been described, but the effect of the present invention is not limited to this. The order of the first retardation plate and the second retardation plate with respect to the incident main illumination light beam may be exchanged. Further, it may be configured such that both the first retardation plate and the second retardation plate are tilted.

Although all of the configurations described above are provided with the first retardation plate and the second retardation plate on the incident side of the liquid crystal cell, the configuration may be provided on the emission side of the liquid crystal cell. In the configuration with a retardation plate on the exit side of the liquid crystal cell, the retardation plate and the substrate that supports it may distort the optical image on the liquid crystal layer, and stray light generated by unnecessary reflection at the interface contrasts. Has a large effect on reducing. Therefore, the first
More preferably, the retardation plate and the second retardation plate are provided on the incident side of the liquid crystal cell.

As the retardation plate used in the liquid crystal display device of the present invention, for example, a stretched transparent resin described below can be used. For example, as an approximation of a positive uniaxial crystal, polycarbonate, polyvinyl alcohol (PVA), polyether sulfone (PES), polyvinylidene fluoride, polyethylene terephthalate (PE
T). For example, polystyrene and polymethylmethacrylate are used to approximate a negative uniaxial crystal.

The first retardation plate and the second retardation plate do not have to be the same retardation plate. Even if the retardation plates are made of different materials, the retardations may be approximately equal. In this case, considering the wavelength dependence of the characteristics of the liquid crystal cell and the retardation plate, an appropriate combination may be used that can achieve good phase compensation for light in a wider wavelength band that is necessary.

On the other hand, it is particularly preferable that both the first retardation plate and the second retardation plate whose optical axes are orthogonal to each other do not give any phase difference to the main illumination light beam in a state where they are orthogonal to the main illumination light beam. . Therefore, it is desirable to use the first retardation plate and the second retardation plate whose characteristics are well matched. If the respective retardation plates are made of the same material and have the same design, the characteristics can be easily made uniform. If two retardation plates that have undergone the manufacturing process of the same lot are used, two retardation plates having the same characteristics can be obtained better.

[0165]

As described above, the liquid crystal display device of the present invention can reduce the light output intensity in the black display state by providing the two retardation plates for effectively performing the phase compensation, and can reduce the arbitrary direction. It is possible to obtain an optical image having a good contrast with respect to the illumination light beam that travels to. Furthermore, if a projection display device is configured using the liquid crystal display device of the present invention, it is possible to realize a projection display device that can present a projected image with good contrast.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating parameters representing the state of elliptically polarized light.

FIG. 2 is a perspective view showing the configuration of the first embodiment of the liquid crystal display device of the present invention.

FIG. 3 is a perspective view illustrating an index ellipsoid representing the function of a retardation plate.

FIG. 4 is a perspective view showing the configuration of a second embodiment of the liquid crystal display device of the present invention.

FIG. 5 is a perspective view showing the configuration of a third embodiment of the liquid crystal display device of the present invention.

FIG. 6 is a schematic diagram illustrating a relationship between a liquid crystal cell and a retardation plate in a YZ cross section direction.

FIG. 7 is a schematic diagram illustrating the relationship between a liquid crystal cell and a retardation plate in the XZ sectional direction.

FIG. 8 is a schematic configuration diagram showing a configuration of a first embodiment of a projection display device of the present invention.

FIG. 9 is a schematic configuration diagram showing the configuration of a second embodiment of the projection display device of the present invention.

FIG. 10 is a characteristic diagram showing the relationship between contrast and viewing angle in an embodiment of the liquid crystal display device of the present invention.

FIG. 11 is a characteristic diagram showing the relationship between contrast and viewing angle in another embodiment of the liquid crystal display device of the present invention.

FIG. 12 is a perspective view showing a configuration of a transparent body included in an embodiment of the liquid crystal display device of the present invention.

FIG. 13 is a perspective view showing a configuration of a transparent body included in another embodiment of the liquid crystal display device of the present invention.

FIG. 14 is a perspective view showing a configuration of a transparent body included in still another embodiment of the liquid crystal display device of the present invention.

FIG. 15 is a sectional view showing a structure of a conventional active matrix TN liquid crystal cell.

FIG. 16 is a perspective view illustrating an alignment state of TN liquid crystal molecules in a state where no electric field is applied.

FIG. 17 is a perspective view illustrating an alignment state of TN liquid crystal molecules in a state where an electric field corresponding to the maximum applied voltage is applied.

FIG. 18 is a characteristic diagram showing an example of the relationship between the contrast and the viewing angle of a conventional liquid crystal display device.

FIG. 19 is a schematic configuration diagram showing a configuration of a conventional projection display device.

FIG. 20 is a schematic configuration diagram showing a configuration of a conventional projection display device.

[Explanation of symbols]

11 incident-side polarizing plate 12, 41, 154, 175 first retardation plate 13, 42, 155, 176 second retardation plate 14 liquid crystal cell 15 emission-side polarizing plate 16 incident-side glass substrate 17 emission-side glass substrate 18 TN liquid crystal Layers 19, 20 Rubbing directions 24, 108, 141, 142, 143 Main illumination rays 25, 26 Polarization axis azimuths 27, 28, 43, 44 Optical axis azimuths 35 Closed containers 101, 121, 122, 123 Liquid crystal display devices 102, 124 Light source 103, 134 Projection lens 104 Screen 125, 126, 131, 132 Dichroic mirror 127, 133 Flat mirror 128, 129, 130 Field lens 151, 171, 172, 184 Transparent body

[Procedure amendment]

[Submission date] August 11, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Equation 1]

[Equation 2]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

[0025]

In order to solve the above-mentioned problems, the liquid crystal display device of the present invention is designed to spatially modulate light to produce an optical signal.
It forms an image and is mainly used for linear deviation in a specific direction.
It has an incident-side polarization means for emitting light and a pixel electrode.
The twist angle between the transparent substrate on the incident side and the transparent substrate on the outgoing side is approximately
Liquid with 90 degree twisted nematic liquid crystal sandwiched
Crystal cell and mainly for linearly polarized light in a specific direction
Approximate the output side polarization means to pass and the positive uniaxial crystal
A first phase difference means and a second phase difference means having a function are provided.
The first phase difference means and the second phase difference means are incident side polarized light.
Means between the liquid crystal cell and the liquid crystal cell
It is arranged in one of the optical paths between the light means and has an incident side polarization hand.
The polarization direction of the step is the long axis of the liquid crystal molecules in contact with the incident side transparent substrate.
Optical image that is approximately the same as or approximately orthogonal to the azimuth
The main rays of the main wavelength that represent the light that forms the
It is referred to as a bright ray, and is a projection T1 of the polarization direction of the incident side polarization means.
Projection T2 of the polarization direction of the emitting side polarization means and the first phase difference means
Projection S1 of the optical axis of and the projection S of the optical axis of the second phase difference means
When 2 is defined on the plane orthogonal to the main illumination ray, T1
And T2 make an angle of about 90 degrees, and S1 and S2 make about 90 degrees.
And T1 and S1 form an angle of about 45 degrees.
To advance through the optical axis of the first phase difference means and the first phase difference means.
The angle formed by the plane orthogonal to the main illuminating ray is ψ1, the second
The optical axis of the phase difference means and the main light traveling through the second phase difference means
The angle formed by the plane orthogonal to the bright ray is ψ2, and the first phase difference is
Means and the second phase difference means are the main illumination when ψ1 and ψ2 are 0 degrees.
Give phase differences of the same magnitude but different signs to the rays
And driven to form the darkest optical image
Light of the main illuminating light after passing through the liquid crystal cell and the output side polarization means
At least one of ψ1 and ψ2 so that the intensity is minimized.
One of them has a predetermined size different from 0 degree.
It

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

The projection display device of the present invention outputs illumination light.
And the illumination light are spatially modulated to form an optical image.
LCD display device and a projector for projecting an optical image on the screen.
And a liquid crystal display device as a liquid crystal display device.
Use the device to adjust the vicinity of the center of gravity of the effective display area of the liquid crystal display device.
The rays that pass through and reach the vicinity of the center of gravity of the entrance pupil of the projection lens are mainly
It is used as an illumination light beam.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

Another projection type display device of the present invention is provided with three primary colors.
A light source that outputs illumination light containing color components and a light source that emits the light
Color separation means to separate the illumination light into three primary colors
The three primary colors of illumination light emitted from the resolving means are spatially modulated.
Liquid crystals that form three optical images corresponding to the three primary colors
The display device and the three primary colors emitted from the three liquid crystal display devices
From the color synthesizing means for synthesizing the illumination light into one and the color synthesizing means
The emitted illumination light is incident and the three optical images are superimposed and
A liquid crystal display device having a projection lens for projecting on a lean
The above liquid crystal display device is used as
, The projection lens passes through the vicinity of the center of gravity of the effective display area.
The main illumination ray is the ray that reaches the center of gravity of the entrance pupil.
Of.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

Still another projection display device of the present invention is a lighting system.
A light source that outputs light and an optical image that spatially modulates the illumination light
LCD device that forms the image and the optical image on the screen.
The projection lens that casts shadows and the direction in which the projection lens is orthogonal to the optical axis
And a liquid crystal display device.
Then, using the above liquid crystal display device,
Center of the entrance pupil of the projection lens
The liquid crystal display device is equipped with the light beam that reaches the vicinity as the main illumination light beam.
At least the first phase difference means or the second phase difference means
Either one changes as the projection lens moves in parallel.
The arrangement state is changed according to the main illumination light beam.
It

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0097

[Correction method] Change

[Correction content]

[0097]

[Equation 17]

[Procedure Amendment 7]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 8]

[Document name to be corrected] Drawing

[Correction target item name] Figure 9

[Correction method] Change

[Correction content]

[Figure 9]

[Procedure Amendment 9]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 20

[Correction method] Change

[Correction content]

FIG. 20

Claims (21)

[Claims] 1. An incident side polarization means for converting an illumination light beam into substantially linearly polarized light, a liquid crystal cell for giving spatially different phase changes to the light emitted from the incident side polarization means, and the light emitted from the liquid crystal cell. Outgoing side polarization means for mainly selectively emitting only light of a specific polarization direction in light, an optical path between the incident side polarization means and the liquid crystal cell, or an optical path between the liquid crystal cell and the emission side polarization means. A first retardation means and a second retardation means arranged in line with each other, wherein the liquid crystal cell has twisted nematic liquid crystal between the incident side transparent substrate and the emission side transparent substrate having pixel electrodes. Are sandwiched so as to be approximately 90 degrees, and the main polarization direction of the light emitted from the incident side polarization means is substantially parallel or substantially orthogonal to the molecular long axis of liquid crystal molecules in contact with the incident side transparent substrate. 1 The phase difference means and the second phase difference means are functionally similar to a positive uniaxial crystal, and the first phase difference means gives the phase difference given to the light ray traveling orthogonal to the optical axis and the second phase difference. The means give substantially the same phase difference to the light rays traveling orthogonal to the optical axis, and the main light ray having a main wavelength representative of the illumination light flux is referred to as a main illumination light ray, and one plane substantially orthogonal to the main illumination light ray. Above, the projection T1 of the main polarization direction of the light emitted by the incident side polarization means, the projection T2 of the main polarization direction of the light emitted by the exit side polarization means, the projection S1 of the optical axis of the first phase difference means, and the above When the projections S2 of the optical axes of the second phase difference means are defined, the T1 and the T2 are made substantially orthogonal to each other, and the S1 is
And S2 are made substantially orthogonal to each other, the angle formed by T1 and S1 is made to be substantially 45 degrees, and a plane orthogonal to the main illumination light beam propagating in the first phase difference means and the optical of the first phase difference means. The angle formed by the axis is ψ1, and the angle formed by the optical axis of the second phase difference means and the plane orthogonal to the main illumination light beam propagating in the second phase difference means is ψ2, so that the blackest display is obtained. At least one of the angle ψ1 and the angle ψ2 is 0 degree so that the light intensity of the main illumination light beam immediately after passing through the liquid crystal cell to which a predetermined voltage is applied and the emission side polarization means is minimized. A liquid crystal display device having a predetermined size different from each other. 2. A phase difference .delta.0 given to the main illumination light beam passing through it by a liquid crystal cell to which a predetermined voltage is applied so that the blackest display is obtained, where the wavelength of the main illumination light beam is .lamda. The optical axis azimuths of the first phase difference means and the second phase difference means are set so that the phase difference δ0 becomes negative when represented by the amount of advance of the phase with respect to the polarization component in the S1 direction (unit is radian). The first phase difference means and the second phase difference means are made of the same phase difference plate, and the refractive index in the optical axis direction of the phase difference plate is Ns for the light of the wavelength λ, and the refractive index in the direction orthogonal to the optical axis is The ratio is Nf, the thickness for a ray traveling orthogonal to the optical axis is D, and the constant is K = Nf / Ns, and the first retardation means is arranged so that the angle ψ1 is approximately 0 degrees, and 2 The phase difference means should be arranged so that the angle ψ2 satisfies (Equation 1). The liquid crystal display device according to claim 1, wherein. [Equation 1] 3. A liquid crystal molecule located in the vicinity of the center of a liquid crystal layer in a liquid crystal cell to which a predetermined voltage is applied so as to achieve the blackest display with each of the optical axes of the first phase difference means and the second phase difference means. 2. The arrangement state of each of the first retardation means and the second retardation means is selected so that each angle formed by the molecular long axis becomes closer to 90 degrees. Liquid crystal display device. 4. Considering an effective light ray group having the same wavelength as the main illumination light ray intersecting the main illumination light ray at a predetermined angle at a point representative of the display area of the liquid crystal cell, and the blackest of the effective light ray groups is considered. A light beam that gives the largest phase difference to the liquid crystal cell to which a predetermined voltage is applied to display is referred to as an auxiliary illumination light beam, and a liquid crystal cell to which a predetermined voltage is applied to provide the blackest display and the output side polarization Retardation (refractive index difference × thickness) of each of the first phase difference means and the second phase difference means is determined so that the light intensity of the auxiliary illumination light beam immediately after passing through the means is minimized. Claim 1
The described liquid crystal display device. 5. An incident side polarization means for converting an illumination light beam into substantially linearly polarized light, a liquid crystal cell for giving spatially different phase changes to the light emitted from the incident side polarization means, and the light emitted from the liquid crystal cell. Outgoing side polarization means for mainly selectively emitting only light of a specific polarization direction in light, an optical path between the incident side polarization means and the liquid crystal cell, or an optical path between the liquid crystal cell and the emission side polarization means. A first retardation means and a second retardation means arranged in line with each other, wherein the liquid crystal cell has twisted nematic liquid crystal between the incident side transparent substrate and the emission side transparent substrate having pixel electrodes. Are sandwiched so as to be approximately 90 degrees, and the main polarization direction of the light emitted from the incident side polarization means is substantially parallel or substantially orthogonal to the molecular long axis of liquid crystal molecules in contact with the incident side transparent substrate. 1 The phase difference means and the second phase difference means are functionally similar to a negative uniaxial crystal, and the first phase difference means gives the phase difference given to the light beam traveling orthogonal to the optical axis and the second phase difference. The means give substantially the same phase difference to the light rays traveling orthogonal to the optical axis, and the main light ray having a main wavelength representative of the illumination light flux is referred to as a main illumination light ray, and one plane substantially orthogonal to the main illumination light ray. Above, the projection T1 of the main polarization direction of the light emitted by the incident side polarization means, the projection T2 of the main polarization direction of the light emitted by the exit side polarization means, the projection S1 of the optical axis of the first phase difference means, and the above When the projections S2 of the optical axes of the second phase difference means are defined, the T1 and the T2 are made substantially orthogonal to each other, and the S1 is
And S2 are made substantially orthogonal to each other, the angle formed by T1 and S1 is made to be substantially 45 degrees, and a plane orthogonal to the main illumination light beam propagating in the first phase difference means and the optical of the first phase difference means. The angle formed by the axis is ψ1, and the angle formed by the optical axis of the second phase difference means and the plane orthogonal to the main illumination light beam propagating in the second phase difference means is ψ2, so that the blackest display is obtained. At least one of the angle ψ1 and the angle ψ2 is 0 degree so that the light intensity of the main illumination light beam immediately after passing through the liquid crystal cell to which a predetermined voltage is applied and the emission side polarization means is minimized. A liquid crystal display device having a predetermined size different from each other. 6. A phase difference .delta.0 given to a main illumination light beam passing through a liquid crystal cell, to which a predetermined voltage is applied so as to obtain the blackest display, as a wavelength of the main illumination light beam. The optical axis azimuths of the first phase difference means and the second phase difference means are set so that the phase difference δ0 becomes negative when represented by the amount of phase advance (in radian unit) with respect to the polarization component in the S2 direction. The first retardation means and the second retardation means are made of the same retardation plate, and the light of wavelength λ has a refractive index of Nf in the optical axis direction of the retardation plate and refraction in the direction orthogonal to the optical axis. The ratio is Ns, the thickness for a ray traveling orthogonal to the optical axis is D, and the constant is K = Ns / Nf, and the first retardation means is arranged so that the angle ψ1 is approximately 0 degrees, and 2 The phase difference means should be arranged so that the angle ψ2 satisfies (Equation 2) The liquid crystal display device according to claim 5, wherein. [Equation 2] 7. An optical path length difference (refractive index difference) that gives substantially the same retardation Γ that the first phase difference means and the second phase difference means have to a light having a wavelength of 540 nm that propagates orthogonally to each optical axis. 6. The liquid crystal display device according to claim 1, wherein the thickness is defined as (x thickness), and 100 nm ≦ Γ ≦ 1000 nm. 8. At least one of the first phase difference means and the second phase difference means is a liquid crystal cell, an incident side polarization means, and an emission side so that at least one of the angle ψ1 and the angle ψ2 can be changed. The liquid crystal display device according to claim 1 or 5, wherein the liquid crystal display device is separated from the polarizing means and has a variable arrangement state. 9. The liquid crystal display device according to claim 1, wherein the first retardation means and the second retardation means are formed by stretching a transparent resin film. 10. The liquid crystal display according to claim 1 or 5, wherein the first phase difference means and the second phase difference means are arranged in an optical path from the incident side polarization means to the liquid crystal cell. apparatus. 11. The first phase difference means and the second phase difference means are phase shifters manufactured in the same lot through the same process based on the same design specifications, as claimed in claim 1 or claim 5. Liquid crystal display device. 12. One of the optical path from the incident side polarization means to the liquid crystal cell or the optical path from the liquid crystal cell to the exit side polarization means, which includes the first phase difference means and the second phase difference means, is transparent. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is filled with a body and optically coupled. 13. The liquid crystal display device according to claim 12, wherein the transparent body is a gel silicone resin. 14. A robust transparent body for holding a first retardation means and a second retardation means on both sides and optically coupling an optical path between the first retardation means and the second retardation means, 6. The liquid crystal according to claim 1, wherein the transparent body is formed by inclining a surface holding one phase difference means with respect to a surface holding the other phase difference means in a predetermined direction by a predetermined angle. Display device. 15. A robust first transparent body and a robust second transparent body, wherein a pair of opposing surfaces of the first transparent body are surfaces A and B, and a pair of opposing surfaces of the second transparent body. Face C and face D,
At least one of the surface A, the surface B, the surface C, and the surface D is inclined by a predetermined angle in a predetermined direction, and the surface A is optically coupled to the incident side transparent substrate of the liquid crystal cell, The surface B is the first phase difference means or the second phase difference means.
Optically coupled to one of the phase difference means and optically coupled to the surface B. The other surface of the phase difference means is optically coupled to the surface C, and the surface D is the other position not optically coupled to the surface B. 2. The optical coupling with the surface of the phase difference means.
Alternatively, the liquid crystal display device according to claim 5. 16. A transparent body which makes a boundary surface with an air layer located at a position closest to the incident side through a medium optically coupled to the incident side from the liquid crystal cell substantially orthogonal to the main illuminating light beam. 16. The liquid crystal display device according to claim 12 or 15. 17. A liquid crystal display device that modulates an illumination light beam to form an optical image, a light source that outputs the illumination light beam, and light emitted from the liquid crystal display device is incident to project the optical image on a screen. A projection lens, the liquid crystal display device according to any one of claims 1 to 16 is used as the liquid crystal display device, and the liquid crystal display device passes through a vicinity of a center of gravity of an effective display area of the liquid crystal display device and A projection display device, characterized in that an illumination light ray reaching a central portion of an entrance pupil is defined as a main illumination light ray. 18. The projection lens has a main illumination immediately after each of the light rays emitted from each part of the effective display area of the liquid crystal display device and reaching the center of the entrance pupil of the projection lens is emitted from the liquid crystal display device. The projection display device according to claim 17, wherein the projection display device is substantially parallel to the light beam. 19. A liquid crystal display device for forming three optical images corresponding to three primary colors by respectively modulating illumination light fluxes of the three primary colors, a light source for outputting light containing color components of the three primary colors, and emitted from the light source. Color separation means for decomposing light to form the three primary color illumination light beams, light combining means for combining the three primary color illumination light beams emitted from the three liquid crystal display devices into one, and combined light emission from the light combining means. The liquid crystal according to any one of claims 1 to 16, further comprising: a projection lens that receives the illumination light flux and projects the three optical images on a screen in a superimposed form. Using the display device, the three illuminating light rays passing through the vicinity of the center of gravity of the effective display area of each of the three liquid crystal display devices and reaching the vicinity of the center of the entrance pupil of the projection lens Projection display apparatus characterized by defining the main illumination ray of the liquid crystal display device. 20. The projection lens emits light from each part of the effective display area of each liquid crystal display device and reaches the center of the entrance pupil of the projection lens. 20. The projection display device according to claim 19, wherein the projection illumination device is arranged to be substantially parallel to each of the corresponding main illumination rays immediately after. 21. A liquid crystal display device that modulates an illumination light beam to form an optical image, a light source that outputs the illumination light beam, and light emitted from the liquid crystal display device is incident to project the optical image on a screen. A liquid crystal display device according to any one of claims 1 to 16, further comprising: a projection lens, the projection lens comprising means for moving in parallel in a direction substantially orthogonal to an optical axis of the projection lens. Is defined as the main illumination light beam that passes through the vicinity of the center of gravity of the effective display area of the liquid crystal display device and reaches the vicinity of the center of the entrance pupil of the projection lens, and proceeds with the movement of the projection lens. The angle φ1 or the angle φ2 is provided with a unit that changes the arrangement state of the first retardation unit or the second retardation unit included in the liquid crystal display device in accordance with the main illumination light beam whose azimuth changes.
A projection display device characterized by changing at least one of the above.